Process for guiding a suspension in a paper stock pulper and a paper stock pulper for conducting the process

ABSTRACT

Paper stock pulper and process for guiding a suspension in paper stock pulper. The stock pulper includes a container having a side wall and front walls adjacent the side wall, and the process includes driving a plurality of rotors to produce a plurality of intake flows directed toward the side wall, deflecting the plurality of intake flows about 90° on the side wall so that the plurality of intake flows flow along at least a part of the side wall, and deflecting, with at least one flow directing device, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls or an adjacent rotor from the at least one front wall or the adjacent rotor.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority under 35 U.S.C. §119 of German Patent Application No. DE 101 38 860.8, filed on Aug. 8, 2001, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a process for guiding a suspension in a paper stock pulper, e.g., a broke slusher arranged under a paper machine, through the operation of a driven rotor, such that an intake flow directed towards the side wall is produced. The intake flow is deflected by approximately 90° on the side wall and then flows along at least a part of the side wall.

[0004] The invention relates to a process for guiding a suspension in a paper stock pulper, e.g., a broke slusher arranged under a paper machine, such that, during the operation of several rotors, several intake flows directed towards the side wall are produced. The intake flows are deflected by approximately 90° on the side wall and then flow along at least a part of the side wall.

[0005] 2. Discussion of Background Information

[0006] It is known that paper stock pulpers are used in the paper industry to dilute with water an inserted raw material containing paper fibers and to slush it up to a certain crushed condition. Such stock pulpers require at least one dissolving organ with a drivable rotor that crushes the inserted paper, thus producing an intake flow in the mixture of water and paper stock, through which the object of a stock pulper can be attained. Although it would be advantageous to install the dissolving organ centrally in the base of the stock container to produce an rotationally symmetrical flow, this is not possible or useful with the paper stock pulpers under consideration here, e.g., because space does not permit. The dissolving organ is therefore arranged laterally in the container of the stock pulper. Although such an arrangement solves the space problem, it usually results in a worse intake of the paper floating on the surface, which is attributable to the fact that the volume flow conveyed by the rotor is distributed asymmetrically in the container, or that the container is not rotationally symmetrical.

[0007] Although a special device for disintegrating and defibrating paper has been known since 1954 from U.S. Pat. No. 2,682,810, where two rotors are located in the side wall, they are arranged concentrically, have different purposes and different rotational speeds. A marked rotational flow concentric to the rotors obviously develops as a result, which flow is diverted by deflectors in a horizontal direction. However, this way of influencing the flow is only useful with a stock pulper of the type disclosed there.

[0008] The most frequent and most important application of stock pulpers with laterally installed dissolving organs is slushing the broke under the paper machine: it is known that there are operating conditions in paper production where already thickened fibrous material or the entire paper web cannot be processed further, but have to be removed from the paper machine as broke. Paper stock pulpers placed underneath the paper machine are used for this purpose, which pulpers are generally called broke slushers. They are relatively wide so as to be able to hold the entire paper web that drops down. A trough width that is more than double the trough height is typical for such broke slushings.

SUMMARY OF THE INVENTION

[0009] The present invention provides a process with which the suspension is moved in the paper stock pulper such that a rapid slushing of the paper collecting over the entire width is possible even in the case of stock pulpers that are not rotationally symmetrical.

[0010] According to the invention, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls is deflected from the front wall by at least one flow directing device. Further, the invention provides that at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls or the adjacent rotor is deflected from the front wall or the adjacent rotor by at least one flow directing device.

[0011] Further, the present invention is directed to paper stock pulpers that include at least one flow directing device projects on the side wall towards which the intake flow is directed, which flow directing device features deflectors the leading edge of which lies geodetically inside the outside diameter of the rotor and is horizontally no further from the center of the rotor than two thirds of the horizontal distance between the center of the rotor and the nearer side wall, and in that the trailing edge of the deflectors lies geodetically outside the outside diameter rotor and is horizontally no further from the nearer front wall than corresponds to a third of the horizontal distance between the center of the rotor and the nearer front wall.

[0012] The process according to the invention leads to an optimum liquid movement in the stock pulper. By the measures described, particularly the portion of the suspension that flows horizontally or almost horizontally along the side wall after the intake flow is diverted is picked up and deflected either upwards or downwards or, after being appropriately divided, in both of these directions. It cannot therefore dam up on the front walls or form harmful vertical eddies. Instead, ideally a large intake eddy forms essentially shaped like a horizontal cylinder, the axis of which runs horizontal and crosswise to the rotor axis. A good intake of the paper that drops down thus takes place across the entire longitudinal extension of the trough, i.e., crosswise to the running direction of the paper machine above it.

[0013] The present invention is directed to a process for guiding a suspension in a paper stock pulper. The stock pulper includes a container having a side wall and front walls adjacent the side wall, and the process includes driving a rotor to produce an intake flow directed toward the side wall, deflecting the intake flow about 90° on the side wall so that the intake flow flows along at least a part of the side wall, and deflecting, with at least one flow directing device, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls from the at least one front wall.

[0014] According to a feature of the invention, the at least a part of the suspension can be deflected downwards by the at least one flow directing device.

[0015] In accordance with another feature of the invention, the at least a part of the suspension flow may be deflected upwards by a flow directing device.

[0016] In accordance with still another feature of the present invention, the at least a part of the suspension flowing upwards on the side wall can be guided back into the container via a curved guide wall.

[0017] Further, an intake eddy can be produced in the container, and an axis of rotation of the intake eddy may run horizontally and crosswise to an axis of the rotor and the intake eddy may rotate upwards on a wall opposite the side wall.

[0018] Moreover, the rotor may be located in the side wall, and an intake eddy can be produced in the container, and the axis of rotation of the intake eddy can run horizontally and crosswise to an axis of the rotor and the intake eddy can rotate upwards on the side wall.

[0019] The paper stock pulper may be positioned under a paper machine as a broke slusher, and the process can further include feeding broke from the paper machine into the paper stock pulper.

[0020] The present invention is directed to process for guiding a suspension in a paper stock pulper. The stock pulper includes a container having a side wall and front walls adjacent the side wall, and the process includes driving a plurality of rotors to produce a plurality of intake flows directed toward the side wall, deflecting the plurality of intake flows about 90° on the side wall so that the plurality of intake flows flow along at least a part of the side wall, and deflecting, with at least one flow directing device, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls or an adjacent rotor from the at least one front wall or the adjacent rotor.

[0021] The present invention is directed to a paper stock pulper to guide a suspension in a paper stock pulper. The pulper includes a container having a side wall, front walls adjacent the side wall, and an open top. At least one rotor is positioned in the side wall, the rotor is structured and arranged for slushing inserted paper and for producing an intake flow directed toward the side wall. At least one flow directing device projects from the side wall, and the at least one flow directing device includes a deflector having a leading edge which lies geodetically inside an outside diameter of the rotor and which is located a horizontal distance from a center of the rotor that is no further than two thirds of a horizontal distance between the center of the rotor and a nearer front wall, and having a trailing edge which lies geodetically outside the outside diameter of the rotor and which is located a horizontal distance from the nearer front wall no further than one-third of a horizontal distance between the center of the rotor and the nearer front wall.

[0022] In accordance with a feature of the instant invention, an angle to the horizontal at the trailing edge may be greater than about 70°.

[0023] According to another feature of the invention, the flow directing device may be located on the side wall.

[0024] Further, at least one flow directing device arranged to deflect the suspension upwards can be located on each side of the rotor. The at least one flow directing devices may be located at a point in the side wall at which the intake flow is directed.

[0025] Moreover, at least one flow directing device arranged to deflect the suspension downwards can be located on each side of the rotor. The at least one flow directing devices may be located at a point in the side wall at which the intake flow is directed.

[0026] The rotor can be arranged such that it has a lateral deviation from a horizontal center of the side wall of at least about 10% of a width of the side wall. The deviation may be directed towards the side wall on which the rotor rotates upwards during operation.

[0027] Still further, an angle of the deflectors with respect to horizontal can increase at least on a part over an extent of their length from the leading edge to the trailing edge. The angle of the deflectors may increase from initially between about −15° to 5° to ultimately between about 70° to 90°.

[0028] According to the invention, the deflectors can project at right angles from the side wall.

[0029] Further, at least 80% of the deflectors can project at least about 50 mm from the side wall.

[0030] Further still, an inside width of the container can be at least twice a height of the container.

[0031] According to another feature of the invention, an inside width of the container can be at least twice a depth of the container.

[0032] In accordance with still yet another feature of the present invention, the at least one rotor can include a plurality of rotors arranged next to one another to produce circulation of the suspension.

[0033] Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

[0035]FIG. 1 diagrammatically illustrates flow conditions formed according to the present invention;

[0036]FIG. 2 illustrates a sectional front view of a paper stock pulper;

[0037]FIG. 3 illustrates a view from above of the paper stock pulper depicted in FIG. 2;

[0038]FIG. 4 illustrates a side view of the paper stock pulper depicted in FIG. 2;

[0039]FIG. 5 illustrates a front view of a rotor/wire area;

[0040]FIG. 6 illustrates special flow directing devices;

[0041]FIG. 7 illustrates geometric conditions in the stock pulper according to the instant invention;

[0042]FIG. 8 illustrates sectional front view of an asymmetrical paper stock pulper;

[0043]FIG. 9 illustrates a paper stock pulper with two rotors.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0044] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

[0045]FIG. 1 is a simple sketch showing the container of a relatively wide stock pulper as a horizontal rectangle. It is filled with suspension that forms liquid level 9. The line of vision is chosen so that intake area 10 of intake flow 4 (cf. FIG. 3) is easily recognized. The circulated suspension is deflected approximately at right angles in the intake area and then flows at first radially along side wall 3. A portion of the suspension flowing off from intake area 10 is first directed at left front wall 5 or at right front wall 5′. The flow directing devices for deflecting the flows are indicated to the left and right of intake area 10. There are both flow directing devices 1 and 1′ guiding upwards and flow directing devices 2 and 2′ guiding downwards.

[0046] Normally the intake flow is produced by a rotor 8 which is installed in side wall 3 of container 11. FIG. 2 shows such a paper stock pulper. The flow conditions that appear during operation correspond to those in FIG. 1. Here, too, the width of the container is much larger than the height, which per se creates unfavorable conditions for the slushing. The flow directing devices can be made of, e.g., welded, curved, sheet metal strips. They feature flow-efficient deflectors 16, 16′, 17, and 17′ arranged at angles α1 and α2 to the horizontal which change along the length of the deflectors from between 0° and 90°. The angle advantageously increases with increasing distance from the intake area, because a low-loss deflection is thus possible. The flow directing devices extend laterally up to the end of side wall 3. Both the angle and the other extent of these flow directing devices can be easily adjusted to the geometric conditions in order to achieve an optimum intake flow. The slushed stock is pumped out through a wire sheet 6 kept clear by rotor 8.

[0047]FIG. 3 shows the same paper stock pulper from above, whereby intake flow 4 to rotor 8 is indicated by arrows in the left-hand part of FIG. 3. A part of a curved guide wall 12, which is fixed horizontally above, is depicted on the right-hand part of FIG. 3, but it is understood that this wall essentially runs across the entire width b of container 11.

[0048] A large, essentially cylindrical intake eddy (arrow 18) can develop in container 11 with particular advantage, which eddy produces a movement on the surface towards side wall 3. It ensures a rapid intake of the paper across the entire width of the container. The momentum of this eddy is caused by the deflection on the flow direction devices already described, in particular by the downward deflection on flow direction devices 2 and 2′. A further intake eddy 19 can be advantageously produced near side wall 3, which intake eddy extends across the entire width of the trough as a result of flow directing devices 1 and 1′ deflecting upwards. It is parallel to the first mentioned eddy with an opposite direction of rotation and results from the recycling of the rising suspension on curved guide wall 12 forming the upper end of side wall 3. The movement direction it caused on the surface is directed away from side wall 3. An intake movement (arrow 20) running across width b of container 11 is produced for the paper that drops down at the place where the two intake eddies 18 and 19 meet on the surface. Wall 21 opposite side wall 3 is markedly rounded in the lower area, which also promotes the formation of the intake eddy.

[0049]FIGS. 1 and 2 are based on the simplified case of a strictly radial outflow from intake area 10. However, deviations from it are possible, depending on the shape and speed of rotor 8, an example of which is shown in FIG. 5. The tangential component of the suspension flowing out of the intake area leads to a deviation b from the connection to the central point of the rotor. This is true at least in the direct outflow area of the rotor, i.e., before the influences of the other suspension flows or the geodetical differences in height in the stock pulper are added. This circumferential movement can give rise to an asymmetrical flow, which may be undesirable. As FIG. 8 shows, the rotor can be installed in a lateral deviation a from the horizontal center 7 of side wall 3, in order to avoid these disadvantages. This is achieved, e.g., by making this displacement to the side on which the rotor rotates upwards (in this case, the left side). Another possibility would be to make the asymmetrical design of the flow directing devices, e.g., drawn more steeply upwards on the left than on the right.

[0050]FIG. 6 shows another example for shaping the flow directing devices. The angles to the horizontal should be selected depending on the relevant conditions and requirements. Here the angle α1′ is negative in the initial part, e.g., so as to be able to deflect the volume flow directed upwards in a low-loss manner. At the end of deflector 17, angle α1″ is 90° (positive). Of course, other shapes are also possible in order to solve the problem according to the invention.

[0051]FIG. 7 shows an advantageous shape and position of the flow directing devices. Accordingly, leading edges 13 and 13′ are to be selected such that they lies geodetically inside the outside diameter of the rotor, i.e., between the two horizontals H1 and H2. Moreover, the horizontal distance from the center of rotor 8 is not greater than two thirds of the horizontal distance between the center of rotor 8 and nearer front wall. In FIG. 7, this area is between the two verticals V1 and V2, or V1 and V2′.

[0052] It is a different case with trailing edges 14, 15, 14′ and 15′. They are outside the field enclosed by horizontals H1 and H2 and inside a field formed by a front wall and verticals V2 and V2′.

[0053] In the case of wide stock pulpers, several rotors can also be used next to one another, so that several intake flows 4 and 4′ are created (cf. FIG. 9). For instance, in the case of two rotors 8 and 8′ in the same side wall 3, two adjacent intake areas are formed. The measures according to the invention can also be applied to such cases, by deflecting the suspension flowing along side wall 3 downwards or upwards. In this case, in addition to the advantages already described, the energy consuming turbulences between adjacent rotors can also be avoided. Instead deflections are also made in this area which improve the intake of the paper dropping down. The flow directing devices 1″, 1′″, 2″ and 2′″ that are suitable for this are embodied in a similar way to those already described and arranged between rotors 8 and 8′.

[0054] It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. 

What is claimed:
 1. A process for guiding a suspension in a paper stock pulper, the stock pulper including a container having a side wall and front walls adjacent the side wall, comprising: driving a rotor to produce an intake flow directed toward the side wall; deflecting the intake flow about 90° on the side wall so that the intake flow flows along at least a part of the side wall; deflecting, with at least one flow directing device, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls from the at least one front wall.
 2. The process in accordance with claim 1, wherein the at least a part of the suspension is deflected downwards by the at least one flow directing device.
 3. The process in accordance with claim 1, wherein the at least a part of the suspension flow is deflected upwards by a flow directing device.
 4. The process in accordance with claim 1, wherein the at least a part of the suspension flowing upwards on the side wall is guided back into the container via a curved guide wall.
 5. The process in accordance with claim 1, wherein an intake eddy is produced in the container, and an axis of rotation of the intake eddy runs horizontally and crosswise to an axis of the rotor and the intake eddy rotates upwards on a wall opposite the side wall.
 6. The process in accordance with claim 1, wherein the rotor is located in the side wall, and an intake eddy is produced in the container, and the axis of rotation of the intake eddy runs horizontally and crosswise to an axis of the rotor and the intake eddy rotates upwards on the side wall.
 7. The process in accordance with claim 1, wherein the paper stock pulper is positioned under a paper machine as a broke slusher, and the process further comprises feeding broke from the paper machine into the paper stock pulper.
 8. A process for guiding a suspension in a paper stock pulper, the stock pulper including a container having a side wall and front walls adjacent the side wall, comprising: driving a plurality of rotors to produce a plurality of intake flows directed toward the side wall; deflecting the plurality of intake flows about 90° on the side wall so that the plurality of intake flows flow along at least a part of the side wall; deflecting, with at least one flow directing device, at least a part of the suspension flowing along the side wall and flowing toward at least one of the front walls or an adjacent rotor from the at least one front wall or the adjacent rotor.
 9. The process in accordance with claim 8, wherein the at least a part of the suspension is deflected downwards by the at least one flow directing device.
 10. The process in accordance with claim 8, wherein the at least a part of the suspension flow is deflected upwards by a flow directing device.
 11. The process in accordance with claim 8, wherein the at least a part of the suspension flowing upwards on the side wall is guided back into the container via a curved guide wall.
 12. The process in accordance with claim 8, wherein an intake eddy is produced in the container, and an axis of rotation of the intake eddy runs horizontally and crosswise to an axis of the rotor and the intake eddy rotates upwards on a wall opposite the side wall.
 13. The process in accordance with claim 8, wherein the rotor is located in the side wall, and an intake eddy is produced in the container, and the axis of rotation of the intake eddy runs horizontally and crosswise to an axis of the rotor and the intake eddy rotates upwards on the side wall.
 14. The process in accordance with claim 8, wherein the paper stock pulper is positioned under a paper machine as a broke slusher, and the process further comprises feeding broke from the paper machine into the paper stock pulper.
 15. A paper stock pulper to guide a suspension in a paper stock pulper, comprising: a container comprising a side wall, front walls adjacent said side wall, and an open top; at least one rotor positioned in said side wall, said rotor being structured and arranged for slushing inserted paper and for producing an intake flow directed toward said side wall; at least one flow directing device projecting from said side wall, said at least one flow directing device comprising a deflector having a leading edge which lies geodetically inside an outside diameter of said rotor and which is located a horizontal distance from a center of said rotor that is no further than two thirds of a horizontal distance between said center of said rotor and a nearer front wall, and having a trailing edge which lies geodetically outside the outside diameter of said rotor and which is located a horizontal distance from the nearer front wall no further than one-third of a horizontal distance between said center of said rotor and said nearer front wall.
 16. The paper stock pulper in accordance with claim 15, wherein an angle to the horizontal at said trailing edge is greater than about 70°.
 17. The paper stock pulper in accordance with claim 15, wherein said flow directing device is located on said side wall.
 18. The paper stock pulper in accordance with claim 15, wherein at least one flow directing device arranged to deflect the suspension upwards is located on each side of said rotor.
 19. The paper stock pulper in accordance with claim 18, wherein said at least one flow directing devices are located at a point in said side wall at which the intake flow is directed.
 20. The paper stock pulper in accordance with claim 15, wherein at least one flow directing device arranged to deflect the suspension downwards is located on each side of said rotor.
 21. The paper stock pulper in accordance with claim 20, wherein said at least one flow directing devices are located at a point in said side wall at which the intake flow is directed.
 22. The paper stock pulper in accordance with claim 15, wherein said rotor is arranged such that it has a lateral deviation from a horizontal center of said side wall of at least about 10% of a width of said side wall.
 23. The paper stock pulper in accordance with claim 23, wherein said deviation is directed towards said side wall on which the rotor rotates upwards during operation.
 24. The paper stock pulper in accordance with claim 15, wherein an angle of said deflectors with respect to horizontal increases at least on a part over an extent of their length from said leading edge to said trailing edge.
 25. The paper stock pulper in accordance with claim 24, wherein said angle of said deflectors increases from initially between about −15° to 5° to ultimately between about 70° to 90°.
 26. The paper stock pulper in accordance with claim 15, wherein said deflectors project at right angles from said side wall.
 27. The paper stock pulper in accordance with claim 15, wherein at least 80% of said deflectors project at least about 50 mm from said side wall.
 28. The paper stock pulper in accordance with claim 15, wherein an inside width of said container is at least twice a height of said container.
 29. The paper stock pulper in accordance with claim 15, wherein an inside width of said container is at least twice a depth of said container.
 30. The paper stock pulper in accordance with claim 15, wherein said at least one rotor comprises a plurality of rotors arranged next to one another to produce circulation of the suspension. 